Fastfood restaurant is one of the fastest growing businesses in Korea. There has been a lack of research, however, fastfood restaurant operators should require affluent information of their consumers. The purpose of this study is, first, to examine the relationship between consumers` involvement and demographic information, second, to investigate the relationship between consumers` involvement and membership card usage, third, to examine the influence of involvement on consumers` satisfaction, forth, to investigate the influence of consumers` satisfactions on brand preference of fastfood restaurant. A survey has been conducted on 218 consumers of “L” fastfood restaurants in Busan. The results showed that a significant relationship between involvement, age and job, and also a significant difference in involvement by membership card usage. Additionally, the results show that consumers` involvement affected satisfaction, and satisfaction influenced brand preference. This study provides the practical marketing strategies for fastfood restaurant operators.